The present invention is related to an on-vehicle multiplex communication system and a manufacturing method thereof, in which a multiplex communication is carried out via a predetermined transmission path among a plurality of multiplex communication apparatuses mounted inside an automobile.
Very recently, various sorts of electronic components mounted on automobiles are introduced. Under such circumstances, various on-vehicle multiplex communication systems capable of communicating plural sorts of signals via a small number of transmission line paths are considerably employed in order to manipulate a large number of output component groups functioning as these vehicle electronic components by a large number of input component groups such as switches.
As a conventional on-vehicle multiplex communication system, there is a distribution-process type on-vehicle multiplex communication system (first prior art) in which each of plural multiplex communication apparatuses owns an input/output circuits, and the respective multiplex communication apparatuses make decisions and function controls. In this first conventional on-vehicle multiplex communication system, the on-vehicle multiplex communication systems are independently designed in accordance with the individual attribute conditions such as vehicle sorts and vehicle destination regions, and both the minimum required input function and the minimum required output function, which are suitable for this attribute condition, are restrictedly applied to design the on-vehicle multiplex communication system. In other words, the first conventional on-vehicle multiplex communication systems are designed on the basis of minimizing total cost of the systems with respect to each of the attribute conditions.
As another prior art communication system, there is such an on-vehicle multiplex communication system (second prior art). That is, input circuits and output circuits, which are capable of accepting all of attribute conditions respectively, are previously set in a plurality of multiplex communication apparatuses. Also, while any one of these multiplex communication apparatuses is employed as a master and all of other multiplex communication apparatuses are used as slaves, only the master apparatus issues a command to all of the slave apparatuses based on its decision so as to control the functions of the slave apparatuses. -This second conventional on-vehicle multiplex communication system owns a major aspect, namely general-purpose characteristics of this communication system rather than total cost of this communication system. Even when the input circuits and the output circuits are unused,- no specific measure is taken in order that the second conventional on-vehicle multiplex communication system can be quickly designed to accept an additional function and a vehicle destination region in a flexible manner.
In the first conventional on-vehicle multiplex communication system, since the unnecessary elements as the input/output elements as to the attribute conditions such as the respective vehicle sorts and the respective vehicle destination regions can be excluded as being permitted as possible, the total cost of this communication can be minimized. However, the completely different on-vehicle multiplex communication apparatuses must be independently developed sodas to accept the attribute conditions such as other vehicle sorts, and other vehicle destination regions. Thus, the developing efficiency of these multiplex communication apparatuses is very lowered.
On the other hand, the second conventional on-vehicle multiplex communication system can relatively flexibly accept other vehicle sorts and other vehicle destination regions, but must install the input circuits and the output circuits, which own the all functions as to the vehicles having all of the attribute conditions. Therefore, a large number of extra, namely unused input/output circuits are required for the system cost. This may cause difficulty in view of reducing the system cost. In particular, as to the output circuit for driving/switching the load, the power electronic elements such as electromagnetic relays may be usually utilized. Thus, the employment of the output circuit capable of realizing all functions adaptable for all vehicles would cause the main factor to increase the system cost.
For instance, the following assumption is required with respect to a certain vehicle destination region (will be referred to as a "first vehicle destination region" hereinafter), specific functions such as foot lamps for respective seats and storage mirrors are required in addition to common output elements (namely, output elements required irrespective of attribution conditions) such as power windows, door locks, and room lamps. On the other hands, the following assumption is required for another vehicle destination region (will be referred to as a "second vehicle destination region" hereinafter), a trunk lid open function is required as a specific function in addition to the common output elements such as power windows, door locks, and room lamps. In this case, the functional differences for both the vehicle destination regions are given as follows: For the first vehicle destination region, there are required the foot lamp function of the seats and the storage mirror function, whereas for the second vehicle destination region, the trunk lid open function is required.
FIG. 10 is a block diagram for indicating the first conventional on-vehicle multiplex communication system provided for the above-explained first vehicle destination region. In this on-vehicle multiplex communication system, distribution type multiplex communication apparatuses 71 to 73 are connected in a bus line manner to a transmission path 74 routed within an automobile. The respective multiplex communication apparatuses 71 to 73 are mutually connected via this transmission path 74 by using a preselected communication system such as a frequency division multiplexing system, a time division multiplexing system, and a code division multiplexing system. In this case, driving motors 75 for the power windows and the door locks are connected to the respective multiplex communication apparatuses 71 to 73. Also, a room lamp 76 is connected to one multiplex communication apparatus 71 (for example, multiplex communication apparatus arranged on driver-sided seat). These driving motors 75 and room lamp 76 are provided as the common output elements required irrespective of the attribute conditions. In contrast, foot lamps 77 for seats and a motor 78 for storing a mirror are provided as the specific function element for the first vehicle destination region in this automobile. As a consequence, output circuits for driving/switching the foot lamps 77 and the motor 78 for storing the mirror are formed also in the respective multiplex communication apparatuses 71 to 73, if required. It should be noted that reference numeral 79 shown in FIG. 10 indicates switches such as a door lock switch and a power window operating switch.
Also, FIG. 11 is a block diagram for indicating the first conventional on-vehicle multiplex communication system provided for the above-explained second vehicle destination region. In this on-vehicle multiplex communication system, distribution type multiplex communication apparatuses 81 to 83 are connected in a bus line manner to a transmission path 84 routed within an automobile. The respective multiplex communication apparatuses 81 to 83 are mutually connected via this transmission path 84. In this case, the common output elements such as a room lamp 86 and driving motors 85 for the power windows and the door locks are connected to the respective multiplex communication apparatuses 81 to 83. Also, a trunk lid unlocking motor 87 for opening a trunk lid is provided as the specific function element for the second vehicle destination region. However, nofoot lamps and motors for storing mirrors are not connected to the respective multiplex communication apparatuses 81 to 83, which is different from the first vehicle destination region (FIG. 10). It should also be noted that reference numeral 89 shown in FIG. 11 indicates switches such as a door lock switch and a power window operating switch.
As apparent from comparison between FIG. 10 and FIG. 11, the respective multiplex communication apparatuses 71 to 73 suitable for the first vehicle destination region, and also the respective multiplex communication apparatuses 81 to 83 suitable for the second vehicle destination region do not own the common point. Therefore, the completely different circuits must be designed, depending upon the attribute conditions such as the vehicle destination regions.
Also, FIG. 12 is a block diagram for indicating the second conventional on-vehicle multiplex communication system. In this on-vehicle multiplex communication system, multiplex communication apparatuses 91 to 93 are mutually connected in a bus line manner to a transmission path 94. In this case, the common output elements such as driving motors 95 for the power windows and the door locks are connected to the respective multiplex communication apparatuses 91 to 93. Also, foot lamps 97 for seats and a motor 98 for storing a mirror are provided as the specific function element for the first vehicle destination region, and at the same time, a trunk lid unlock motor 99 for opening a trunk lid is provided as the specific function element for the second vehicle destination region. This second conventional on-vehicle multiplex communication system can be provided for any of the vehicle destination regions. Conversely, in other words, all of such functions become unnecessary when the attribute conditions such as the vehicle destination region are changed. As a result, a large number of useless circuits are employed in all of the vehicles. There is a problem that the total cost is increased.